As a storage system, a cluster type storage system is known which comprises a plurality of nodes that function as controllers or file servers for performing data input/output processing with respect to storage devices which a disk array apparatus comprises, and in which cluster type storage system each node is connected via a network. In a storage system of this type, there exists technology which provides a client (client computer) with a global namespace (hereinafter also referred to as GNS) which is a virtualized simple namespace common to each node (see PTL 1).
Here, a plurality of clients, connected via a network to a cluster type storage system, are capable, by using a GNS, of accessing a single file system which is constructed in a storage system, for example, without knowing the names of the individual nodes. In such a case, if any of the plurality of nodes receives an access request from a client, the node which receives the access request checks the unused capacity of the storage area (logical volume) of each node from the standpoint of capacity distribution, and when its own unused capacity is maximum, accesses its own storage area, and when there is a node among the other nodes for which the unused capacity is maximum, selects a node among the other nodes in which data is to be stored, and transfers data via an internal network to the selected node.